The invention concerns a curtain-wall fa.cedilla.ade structure and a fa.cedilla.ade slab for a fa.cedilla.ade structure of this type. The invention also concerns a extrusion press tool for manufacturing a fa.cedilla.ade slab of this type.
A fa.cedilla.ade with fa.cedilla.ade slabs according to the main concept of claim 1 is known from DE-PS 34 01 271. These fa.cedilla.ade slabs consist of flat front and rear slab segments that are connected by stud links. Additionally, the back face of the slabs has a head and a foot lap that when the slab is mounted are positioned one beneath the other. Furthermore, the front lower edge of the fa.cedilla.ade slabs has a drainage lap that when the slab is mounted fits over the head lap of the slab below it in such manner that the front surfaces of the upper and lower fa.cedilla.ade slabs lie flat on one plane. The head lap of the lower fa.cedilla.ade slabs and the slab holders of the drainage lap or top fa.cedilla.ade slabs are covered in such manner that the holders are only partially visible. Between the foot lap of the upper fa.cedilla.ade slab and the head lap of the lower fa.cedilla.ade slab there is an open horizontal groove for ventilation of the fa.cedilla.ade. The fa.cedilla.ade slabs described are marketed in mill-finished, polished, and sandblasted surfaces.
Additionally, curtain-wall fa.cedilla.ade slabs are known that are less strong and are designed without perforations and without head, foot, and drain laps. These slabs are joined with open horizontal grooves of various widths. These fa.cedilla.ade slabs also are offered in mill-finished, polished, and sandblasted versions, and also in the form of decorative slabs with specific incised decoration.
In curtain-wall fa.cedilla.ades that are ventilated from behind, the grooves must be sufficiently open to permit a change of air to carry away the moisture diffused through the building wall. Through the pulsating effect of the wind, there is adequate ventilation through the open grooves of the fa.cedilla.ade slabs, which are overlapped like scales or abut one another on one plane. In rainy weather, particularly in the case of a driving rain, the water runs down the front of the fa.cedilla.ade slabs. Through the scale-like overlapping of fa.cedilla.ade slabs or the design of the overlapping head and drain laps the water drainage is improved in such manner that practically no driving rain can penetrate behind the fa.cedilla.ade slabs, yet ventilation and consequent exchange of moisture through the open horizontal grooves is not impeded.
The disadvantage of these known fa.cedilla.ade structures is that in the upper region of buildings, that is, near the roof edge, a strong wind can drive rainwater through the open horizontal grooves. The wind striking the building fa.cedilla.ade frontally collects on the fa.cedilla.ade and flows along both sides to the left and to the right and also upward near the top of the fa.cedilla.ade. In the case of tall buildings, particularly when the wind is strong, updriving wind velocities of such power can be reached in the upper reaches of the fa.cedilla.ade that the fa.cedilla.ade water stops flowing downward and is instead driven upward by the wind and, despite the overlapping of head and foot laps, is driven in large quantities through the open horizontal grooves behind the curtain-wall fa.cedilla.ade.
In the perforated slab according to DE-PS 24 01 271 there is a further disadvantage in that on the front surface, which during drying of plastic ceramic blanks is positioned at the top, in the area of the T-shaped cross-section formed by the front slab segment and the stud links, there is an accumulation of material that causes the formation, not only during drying, of shrinkage movements that take the form of optically unaesthetic flat depressions. In materials that are very sensitive to dryness the strong shrinkage movements can even lead to cracks.
DE-OS 25 01 323 discloses fa.cedilla.ade slabs for cladding building exteriors, which said slabs have recesses to give them the appearance of a brick or stone wall.
US-PS 52 13 870 discloses cladding slabs that have ornamental recesses.
US-PS 42 88 956 discloses cladding slabs made of rigid expanded polyurethane with recesses to hold attachment components.
Fa.cedilla.ade slabs having the cross-section shown in FIG. 5 have also become known. These fa.cedilla.ade slabs have a front slab segment 41 and a back slab segment 42 connected by link studs 43, 44, 45, forming core holes 46, 47 between them. The front face of the front slab segment 41 has horizontal grooves 48, 49, 50. The back face 51 of front slab segment 41 follows essentially the contour of the front face of front slab segment 41, so that this front slab segment has essentially the same wall thickness a throughout. Accordingly, near grooves 48, 49, 50 in front slab segment 41 there are joggles 52, 53, 54, 55, 56, 57, the result being that core holes 46, 47 are no longer rectangular compared to the original form without grooves 48, 49, 50; rather, they have indentations that correspond to joggles 52-57.